Structural composite fan exit guide vane for a turbomachine

ABSTRACT

A structural composite fan exit guide vane assembly uses single component monolithic structural guide vane segments to provide airflow correction and structural support in a gas turbine engine.

BACKGROUND

The present disclosure is directed toward turbomachine assemblies and more particularly, toward a structural fan exit guide vane for use in a gas turbine engine.

Turbomachines, such as gas turbine engines, draw air or other gases into the machine using a fan component. The rotation of the fan blades drawing the air in causes the incoming air to swirl in the direction of the fan's rotation. In order to operate the turbomachine properly, however, the air must pass axially through the turbomachine. To rectify the radial swirling of the air, turbomachines include fan exit guide vanes that straighten the air flow behind the fan blades.

Fan exit guide vanes assemblies include multiple vanes, each of which has an airfoil shaped profile that is aerodynamically designed to force the airflow passing through the fan exit guide vane into an axial flow path. Also included within turbomachine assemblies is a separate fan frame that supports the engine core, the fan, and the fan case. The fan frame also maintains the concentricness of the fan case, and the fan blades, and the engine core, thus providing for proper fan tip clearance between the engine shroud and the fan blades.

SUMMARY

A structural composite fan exit guide vane segment includes a single monolithic component having an inner diameter shroud, an outer diameter shroud, and a plurality of fan exit guide vanes connecting the inner diameter shroud and the outer diameter shroud.

A gas turbine engine has a fan frame composed of a plurality of fan exit guide vane segments. Each of the fan exit guide vane segments has a single monolithic component with an inner diameter shroud, an outer diameter shroud, and a plurality of fan exit guide vanes connecting the inner diameter shroud and the outer diameter shroud.

A method is disclosed for creating a fan exit guide vane segment that includes the steps of creating a semi-continuous fiber preform by looping fibers in a desired profile, and infusing the fiber preform with a resin during a molding process thereby creating a single monolithic fan exit guide vane segment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a partial side view of an air intake for the gas turbine engine of FIG. 1A.

FIG. 1B illustrates a front view of the air intake for a gas turbine engine.

FIG. 2 is a contextual drawing of a structural fan exit guide vane assembly.

FIG. 3A illustrates a first isometric view of a structural fan exit guide vane segment.

FIG. 3B illustrates a second isometric view of the structural fan exit guide vane segment of FIG. 3A.

FIG. 4 illustrates a partial isometric view of a fan exit guide vane assembly outer diameter shroud.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1A illustrates a partial side view of an air intake for a gas turbine engine 10. FIG. 1B illustrates a front view of the gas turbine engine 10 with a cutout view 60 illustrating the fan exit guide vanes 50 behind the fan blades 30.

Referring to FIG. 1A, the gas turbine engine 10 has an air intake fan 40 that rotates fan blades 30 radially about an axis A. The rotation of the fan blades 30 draws air into the gas turbine engine 10 along a flow path 32. The fan 40 is encased in a fan case 20, such as a turbine engine shroud. As the air passes through the fan blades 30, the air begins swirling radially relative to axis A due to the rotation of the fan blades 30.

In order to straighten the flow path 32, and allow the air to flow axially through the gas turbine engine 10, the air is passed through a multiple of structural fan exit guide vane segments 50. Each of the structural fan exit guide vane segments 50 includes multiple foil shaped guide vanes 52. Each guide vane 52 is connected to an inner diameter shroud 58 and an outer diameter shroud 56. Each of the outer diameter shrouds 56 are connected to the fan case 20. Each of the inner diameter shrouds 58 are connected to an engine core 42.

In addition to straightening the flow path 32 through the gas turbine engine 10, the structural fan exit guide vanes 50 provide structural support to the engine core 42 and the fan case 20, thereby ensuring that proper clearance is maintained between the tips of the fan blades 30 and the fan case 20. Additionally, the structural support of the structural fan exit guide vane segments 50 maintains the concentricness of the engine core 42, the fan blades 30, and the fan case 20.

FIG. 1B illustrates a front view of the gas turbine engine 10, with a cutout segment 60 illustrating the structural fan exit guide vane segments 50 positioned axially behind the fan blades 30. Each of the structural fan exit guide vanes segments 50 includes a first exit guide vane 52 and a second exit guide vane 54. The outer diameter shroud 56 of each structural fan exit guide vane segment 50 abuts the outer diameter shrouds of each adjacent structural fan exit guide vane segment 50 resulting in a circular structural fan exit guide vane segment assembly behind the fan blades 30. The structural fan exit guide vane assembly structurally supports the engine core 42, the fan blades 30, and the fan case 20 and axially straightens the flow path 32. As with the outer diameter shrouds 56, each of the inner diameter shrouds 58 abuts the inner diameter shrouds 58 of each adjacent structural fan exit guide vane segment 50.

The above described configuration with each structural fan exit guide vane segment 50 abutting two adjacent fan exit guide vane segments 50 creates a circular structural fan exit guide vane assembly that provides the structural support described above, and the airflow straightening described above, while at the same time not requiring a separate structural frame assembly to support the fan 40, the fan case 20, and the engine core 42.

FIG. 2 illustrates a more detailed contextual side drawing of a single structural fan exit guide vane 100. The outer diameter shroud 156 and the inner diameter shroud 158 of the structural fan exit guide vane 100 are connected by guide vanes 152, 154. Each of the shrouds 156, 158 is fastened to the fan case 20 and the engine case 42 via a plurality of fasteners 170, such as bolts. The fasteners 170 protrude through the shrouds 156, 158 and into the fan case 20 and the engine core 42. Each of the inner diameter shroud 158 and the outer diameter shroud 156 also includes a fiber bulge 160, resulting from the molding process, that physically contacts the fan case 20 (in the case of the outer diameter shroud 156) and the engine core 42 (in the case of the inner diameter shroud 158).

FIG. 3A illustrates an isometric view of a structural fan exit guide vane segment 200 that can be used as the structural fan exit guide vane segment 50 of FIGS. 1A and 1B. The structural fan exit guide vane segment 200 includes an arced outer diameter shroud 256 and an arced inner diameter shroud 258 with each of the arcs being coaxial. The shrouds 256, 258 are connected via a two fan exit guide vanes 252, 254. Each of the shrouds 256, 258 also includes multiple counter sunk holes 272 for fastening the shrouds 256, 258 to the fan case 20 and the engine core 42. The arcing of the shrouds is concentric. The countersinking of the fastener bolts 272 allows the fastener heads to be flush with the exposed surface of the shrouds 256, 258, thereby minimizing the effect of the fasteners on the airflow along the flow path 32 through the gas turbine engine 10.

Also attached to both the inner and the outer diameter shrouds 256, 258 is an integral flow path spacer 280. The integral flow path spacer 280 on the outer diameter shroud 256 is visible in FIG. 3A, while the integral flow path spacer 280 on the inner diameter shroud 258 is hidden due to the view angle. The integral flow path spacer 280 provides an airflow seal between each structural guide vane 200 and the adjacent structural guide vanes 200.

Due to the circular nature of the structural guide vane assembly, the integral flow path spacer 280 is only placed on a single shroud edge of each of the inner and outer diameter shrouds 256, 258. When assembled, each shroud edge with a spacer abuts an edge of an adjacent shroud 256, 258 without a spacer resulting in each abutment being sealed by a single integral flow path spacer 280.

Each of the guide vanes 252, 254 has an airfoil shaped profile that allows the vanes 252, 254 to force air passing through the structural fan exit guide vane assembly into an axial flow path. The particular foil profile of the vanes 252, 254 can be designed according to known techniques to fit the requirements of a particular gas turbine engine implementation.

FIG. 3B illustrates an alternate viewpoint of the structural guide vane assembly of FIG. 3A, with like numerals indicating like elements. The view shown in FIG. 3B shows the integral flow path spacer 280 on each of the inner and outer diameter shrouds 256, 258. Also illustrated is the fiber bulge 260 on the inner diameter shroud 256. The isometric view of FIG. 3B further illustrates the foil profile of the guide vanes 252, 254.

FIG. 4 provides a zoomed isometric view of the outer diameter shroud 256 and the integral flow path spacer 280 of FIGS. 3A and 3B. The integral flow path spacer 280 is a solid piece of flexible material, such as rubber, and includes a seal portion 282 and a connection portion 284. The seal portion 282 overhangs the edge of the outer diameter shroud 258. When the structural guide vane segment 200 abuts an adjacent guide vane segment, the seal portion 282 deforms to provide an airtight seal between the two outer diameter shrouds 256. The seal portion 282 also provides vibrational damping between the structural guide vane segments 200. The connection portion 284 of the integral flow path spacer 280 is affixed to the shroud segment, attaching the integral flow path spacer 282 to the shroud. A similar integral flow path spacer 282 design is used with the inner diameter shroud 258.

The structural fan exit guide vane segments described above and illustrated in the figures, use a single monolithic carbon/epoxy structure to construct the guide vane segment as a single piece. In order to create the single monolithic guide vane segment, the two vanes are shaped into a preform having the desired airfoil profile using a continuous or semi-continuous fiber. The fiber preform is then infused with a carbon/epoxy resin during a molding process. This type of resin molding generates an end component that is a single piece and is constructed of a fiber reinforced polymer matrix composite. The molding process also creates the inner and outer diameter shrouds using standard carbon/epoxy laminate molding processes. The counter sunk holes can either be created as part of the molding process or drilled after the molding process is finished. In an alternative example, three or more guide vanes can be constructed in the same manner, and could be used in each monolithic vane segment and still fall within the above disclosure.

Although embodiments of this invention have been disclosed, a worker of ordinary skill would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention. 

1. A structural composite fan exit guide vane segment comprising: a monolithic component having an inner diameter shroud; an outer diameter shroud; and a plurality of fan exit guide vanes connecting said inner diameter shroud and said outer diameter shroud.
 2. The structural composite fan exit guide vane segment of claim 1, wherein said monolithic component is constructed of a composite material.
 3. The structural composite fan exit guide vane segment of claim 2, wherein said composite material comprises a carbon/epoxy laminate molding.
 4. The structural composite fan exit guide vane segment of claim 1, wherein said inner diameter shroud comprises at least one counter sunk hole operable to connect said inner diameter shroud to an engine frame.
 5. The structural composite fan exit guide vane segment of claim 1, wherein said outer diameter shroud comprises at least one counter sunk hole operable to connect said outer diameter shroud to an engine casing.
 6. The structural composite fan exit guide vane segment of claim 1, further comprising an integral flow path spacer affixed to a single side of said outer diameter shroud.
 7. The structural composite fan exit guide vane segment of claim 1, wherein each of said fan exit guide vanes has an airfoil shaped profile.
 8. The structural composite fan exit guide vane segment of claim 1, wherein said plurality of fan exit guide vanes comprises exactly two fan exit guide vanes.
 9. The structural composite fan exit guide vane segment of claim 1, wherein said plurality of fan exit guide vanes comprise a fiber reinforced polymer matrix composite.
 10. The structural composite fan exit guide vane segment of claim 1, wherein said inner diameter shroud is an arc segment having a first radius, said outer diameter shroud is an arc segment having an second radius, and said second radius is larger than said first radius.
 11. A gas turbine engine comprising; a fan; and a fan frame supporting said fan comprising a plurality of fan exit guide vane segments, each of said fan exit guide vane segments having a single monolithic component having an inner diameter shroud, an outer diameter shroud, and a plurality of fan exit guide vanes connecting said inner diameter shroud and said outer diameter shroud.
 12. The gas turbine engine of claim 11, wherein said inner diameter shroud comprises a plurality of counter sunk holes, and wherein a fastener protrudes through each of said plurality of counter sunk holes thereby fastening said fan exit guide vane segment to said frame.
 13. The gas turbine engine of claim 11, wherein said outer diameter shroud comprises a plurality of counter sunk holes, and wherein a fastener protrudes through each of said plurality of counter sunk holes thereby fastening said fan exit guide vane segment to an engine casing.
 14. The gas turbine engine of claim 12, wherein each of said plurality of fan exit guide segments abuts at least two adjacent fan exit guide vane segments.
 15. The gas turbine engine of claim 14, further comprising an integral flow path spacer operable to create a seal between each abutting outer diameter shroud.
 16. The gas turbine engine of claim 14, further comprising an integral flow path spacer operable to create a seal between each abutting inner diameter shroud.
 17. The gas turbine engine of claim 12, wherein a head of each said fasteners is flush with such counter sunk holes.
 18. The gas turbine engine of claim 11, wherein each of said plurality of fan exit guide vanes segments structurally supports said gas turbine engine.
 19. The gas turbine engine of claim 18, wherein said gas turbine engine is structurally supported at a gas exit via only said fan exit guide vane segments.
 20. A method for creating a fan exit guide vane segment comprising the steps of creating a fiber preform by looping a fiber in a desired profile; and infusing said fiber preform with a resin during a molding process thereby creating a single monolithic fan exit guide vane segment.
 21. The method of claim 20, wherein said looped fiber is substantially a structurally continuous loop.
 22. The method of claim 20, wherein said looped fiber is substantially a structurally semi-continuous loop.
 23. The method of claim 20, wherein said resin is a carbon/epoxy resin. 